An apparently berserk man was shot and killed by two off-duty detectives yesterday evening after he bailed out of a car on a busy Queens highway and began pummeling the cops, who had stopped to see what happened, police said last night.

The man tentatively identified as Dandre Darnell, was killed after the detective sergeant and his female detective companion opened fire to protect themselves, sources said.

Details of the incident were sketchy last night, but police officials provided the following account:

Darnell, 25, of Glen Cove. L.I. was a passenger in a Kia traveling southbound on the Grand Central Parkway near Francis Lewis Boulevard, at about 6:35 p.m., when, for unclear reasons, he suddenly rolled out of the car’s passenger door.

The driver of the Kia, Russell Ballinger, 25, of Glen Cove, told investigators that he was driving at about 35 to 40 miles per hour when Darnell bolted.

A livery car behind the Kia swerved to avoid Darnell, who was sprawled on the ground.

When the detectives, who had just gotten off duty and were car-pooling to Long Island, stopped their Dodge pickup truck to see what had occurred, Darnell jumped up, went to the driver’s side of the truck and began assaulting the sergeant, Stephen Borchers.

After punching him, Darnell allegedly ran to the woman detective, Jean Weller, in the passenger seat and tried to pull her through her window.

Cops said Weller, a 15-year veteran, resisted by striking Darnell in the head several times with her .38 caliber revolver – then fired at him three times.

Borchs, a 13-year veteran, who was driving the van also fired at least once, with his 9mm Glock semi-automatic.

At least one shot hit Darnell in the chest and he was dead at the scene, cops said.

Both detectives were taken to Long Island Jewish Hospital and “displayed injuries consistent with witness accounts of what occurred,” a police spokesman said.

Sources said Ballinger was cooperating with the investigation, along with the livery driver and two other witnesses -but there was no immediate explanation for Darnell’s behavior.